Ratio, proportion and percentages

From politics to cookery, ratios, proportions and percentages are part of everyday life...

From politics to cookery, ratios, proportions and percentages are part of everyday life. This unit is designed to help you become more familiar with how figures can be manipulated, then you can check whether that discount really is as big as they claim!

By the end of this unit you should be able to:

work with simple ratios;

convert between fractions, decimals and percentages;

explain the meaning of ratio, proportion and percentage;

find percentages of different quantities;

calculate percentage increases and decreases;

calculate average speeds in given units and find speeds, distances and times for travel at constant speed;

Ratio, proportion and percentages

Introduction

This unit is from our archive and it is an adapted extract from Open mathematics (MU120) which is no longer in presentation. If you wish to study formally at The Open University, you may wish to explore the courses we offer in this subject area [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] .

The topics in this unit, ratios, proportion and percentages, are concerned with dividing something into parts. For example, if there are 200 people living in a small village, and 50 of these are children, this could be expressed as a percentage:

25% of the village population are children;

or as a ratio:

one in every four people is a child or there is 1 child for every three adults;

or a proportion:

the proportion of children in the village population is a quarter.

One difficulty that some people find with these topics is knowing when to multiply and when to divide. This module revises the relevant techniques and helps you to apply them logically.

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